Implicating big_ben → clock_tower
Link to implication

Reason:

Big Ben is the nickname usually used to refer to both the clock and the clock tower.

-1

its possible to depict big ben in recognizable manner as a silhouette, but for clock tower tag, it would need to be recognizable as a clock tower even for people who do not know what big ben is.

for example in this image you can recognize it as big ben from shape, but clock tower wouldnt apply since there is no way identify it as a clock tower without relying on external knowledge.

Ajk is right that "Big Ben" is the nickname for the largest bell in the tower and that the name is often applied (wrongly) to the tower itself, but the clock tower itself is actually the Elizabeth Tower attached to the Houses of Parliament. Not that even most Londoners are going to know that, of course. :p

To be honest, I'm leaning towards Hiekkapillo's interpretation. Part of recognizing the Elizabeth Tower as the home of Big Ben is the clock face. If we can't see the clocks, we really can't be sure it's a clock tower.

Yup, denied for the reasons above.

It could also just use "landmark" tag in tandem with "clock_tower" tag

zanjll said:
It could also just use "landmark" tag in tandem with "clock_tower" tag

Clocktower is already proven as an invalid implication, but I'd be okay with it implying landmark.